Process of making indigo-white.



no. reacts.

Patented July 4, recs.

.TREWT 1 Plllllh SElDltli AND ROBERT Wllh TMER, OF LUDWlUrfilldlildhl-UNTHE-ltl lllfil l, GERMANY, ASSTGNURS TU BADISCHE Al llLlN d: S OlMt liAElltlli, OF LUD- WTGSHAFEN-ON-THE-RHTNE, GERMANY, A CORPORATTUN UF BADEN.

lF'PEGTJFTGATTON forming part oi" Letters "Patent No. 79'l,lldl3 dated July at, 19055,

Application filed llpril 12, 190i. burial in. scant-r.

To all whom it may concern:

i c it known that we, PAUL Simona, a subject oi the King of Saxony, and llonnlrr WIM- MEn, a subject oi the King of Bavaria, doctors 1-; oi philosophy and chemists, residing at Lud wigshaien-on-the-lthine, in the Kingdom oi lfiavaria, German Empire, have invented new and useful llmprovements in the Production of indigo-White, of which the following is a to specification.

When-manufacturing indigo according to the more important processes, indoxyl and indoxylic acid, hereinafter referred to as indoxylic bodies," are obtained as intermediate products, and these are oxidized to indigo, hor use the indigo has to be reduced again to iudigo-white. l lo process by which indoxylic bodies could be oxidized to indigo-white has hitherto been lrnown. We have now discovtv ered that indoxylic bodies can be oxidized to indigo-white by using a quantity of oxidizing" agent insumcient to oxidize the whole to indigo. We have further discovered that indigo is itsell a suitable oxidizing agent for 5 oxidizing indoxylic bodies to indigo-white,

and at the same time it is itself reduced to indigo-white. For the purposes of our invention we may, for instance, proceed by blowing through a solution of an indoxylic body a a quantity of air sufiicient to oxidize the whole to indigo-white, but insufiicient to oxidize it all to indigo, or when indigo is used as the oxidizing agent we may proceed by acting upon a quantity of an indoxylic body with such a quantity of indigo that asolutiou containing practically only indigo-white results.

It is not necessary to isolate the indoxyl and indoxylic acid before carrying out this reaction, as the alkaline melt obtained in the usual t preparation of these compounds can be employed. We have further discovered that by using a small quantity of certain bodies, which We call oxygen-carriers -such as iron salts, alkali sulfites, &c.-the speed of this reaction is increased. The alkali solution of indigowhite which results in eitheroot the foregoing cases can be filtered from any indigo which is present and can be further treated as desired.

The following examples will serve to fur-- ther illustrate the nature of our invention, 5

which, however, is not confined to these ex" amples. The parts are by weight.

Example 1: To one thousand (1,000) parts of hot water add two hundred (E200) parts oi a ten (10) per cent. indoxyl melt. Pass a strong current oil air through the liquid until indigo begins to separate out freely, and then filter. llndigo white can be precipitated out ,of the filtrate by passing carbondioxid through the solution. 6o

Example 2: fiuspend thirty-five (35) parts oil finely-divided indigo in two thousand (2,000) parts of water and heat the whole to a tomperature'oi about ninety degrees centigrade, (90 (1.) Then add gradually while stirring four, hundred (400) parts of a nine (9) per cent. indoxyl melt. After a short time the solution becomes deep orange-red and the indigo goes into solution as indigo-white The excess oil free alkali can then be removed by any of the known methods and the solution is ready for use in the dyebath.

Example 3: lfiuspend thirty-live (35) parts oll' finely-divided indigo in two thousand (2,000) parts oi boiling water and add, first, a solution of two and a halt (2.5) parts oi ferrous sulfate and then three hundred (300) parts oi a twelve (12) per cent. indoxyl melt. The indigo goes rapidly into solution.

What we claim is-- l. The process tor the production of indigowhite, which consists in oxidizing an indox ylic body with aquantity of oxidizing material insufiicient to oxidize the whole to indigo.

2. The process for the production of indigo- 5 white, which consists in oxidizing an indox ylic body with a quantity of oxidizing mate rial insuflicient to oxidize the whole to indigo, in the presence of an oxygen carrier.

3. The processfor the production of indigowhite, which consists in oxidizing an indoxylic body with a quantity of oxidizing mate rial insufficient to oxidize the whole to indigo, in the presence of an iron salt.

it. The process for the production of indigowhite, which consists in oxidizing indoxyl with a quantity of oxidizing material insufiicient to oxidize the whole to indigo.

5. The process for the production of indigowhite, which consists in oxidizing indoxyl with a quantity of oxidizing material insufiicient to oxidize the whole to indigo, in the white'which consists in oxidizing indoxyl 1 using indigo as the oxidizing agent, in the presence of an oxygen-carrier.

9. The process for the production of indigo- 20 white which consists in oxidizing indoxyl,

using indigo as the oxidizing agent, in the presence of an iron salt.

In testimony whereof we have hereunto set our hands in the presence of two subscribing 5 witnesses.

PAUL SEIDEL. ROBERT WIMMER.

Witnesses:

ERNEST F. EHRHARDT, J. ALEo. LLOYD. 

